The invention relates to a method of mixing cosmetic preparations composed of at least two components, which can be in liquid or paste form, and which have to be mixed together immediately prior to use, especially for mixing a ready-to-use hair dye preparation immediately before use, and it relates to a set of apparatus for the practice of the method.
Certain cosmetic preparations have to be mixed immediately prior to use because they are composed of two or more substances which react with one another chemically after being mixed, and which no longer produces the desired effect after this reaction has ended. This is the case, for example, with hair dye preparations which are made from the actual dye in liquid or paste form and a liquid oxidant just prior to application to the hair, and then have to be used immediately, i.e., applied to the hair. In the use of these hair dyes the procedure has hitherto been for the user, i.e, the hairdresser as a rule, to place the required amount of the components into a dyeing dish, mix them together, and then apply the mixture immediately to the customer's hair. In this procedure, the hairdresser must first measure the components relatively precisely, because if they are not in correct proportion the desired tint will not be achieved. The dye component in paste form has formerly been measured out either by forcing a strand of it from the tube containing it, to a length selected as the measure of the quantity, or the dye has been forced from a tube calibrated by uniform marking, until the desired mark is reached. It can readily be understood that the determination of quantity by measuring the length of the strand from the tube or by forcing out the contents of the tube until a certain mark is reached is imprecise, because in the one case the strand from the tube will have a greater or lesser diameter according to whether it has been stretched or compressed, so that such strands of equal length can contain different amounts of the components, while in the other case the imprecision is to be attributed to the fact that when the tube is squeezed out to a certain mark, the tube containing the rest of the contents may also have been narrowed down to a greater or lesser extent so that differences can be produced. The liquid component can be measured more precisely by using a graduate, but this is of no benefit if the paste dye component is not correctly measured. Measuring the liquid component with a graduate is furthermore a nuisance, and it is not impossible that the precisely measured amount of liquid might not all be poured out into the mixing dish.